There are many circumstances where poultry hatchlings must be treated when they first emerge. Such treatment can include administration of therapeutic agents or it may simply involve maintaining the hydration of the hatchlings during holding and transport. There are many therapeutic agents which are used in the raising of poultry: vaccines, competitive exclusion products, vitamins, minerals, medicaments and many others. A number of such therapeutic agents must be protected from environmental effects while being delivered to the hatchlings.
In particular, poultry hatchlings, within the first few days of life, are required to be immunized against various diseases and the type of vaccine used for each disease dictates its method of administration. Vaccines are usually administered in the hatchery by injection at the time of sorting of the hatchlings from the hatching incubator into holding or transporting trays. Live vaccines may be administered once the hatchlings are established in their brooding areas in the form of aqueous suspensions, either sprayed on feed or added to the drinking water.
One example of a live vaccine is that used to immunize poultry against coccidiosis caused by protozoa of the genus Eimeria. Coccidiosis is a very common disease of poultry and there are several species of Eimeria which are known to cause such disease. The symptoms and severity of the disease are dependent upon the species of Eimeria with which the bird is infected with E. tenella, E. acervulina and E. maxima being three of the most prevalent species in commercial chickens. At the present time, the protection of poultry against coccidiosis involves two possible methods—use of anticoccidials as feed additives or immunization using a coccidiosis vaccine with immunization being increasingly the preferred route. Coccidiosis vaccines are, at present, comprised of an attenuated or unattenuated species of coccidia in a suitable carrier for administration, the coccidia being capable of causing a mild form of the disease and selected to be anticoccidial susceptible.
One common method of immunization against coccidiosis involves the use of on-feed spray administration while the birds are feeding from flats or other containers. A vaccine comprising of oocysts of Eimeria species using water as a carrier is sprayed onto the feed to be provided to the hatchlings. The use of on-feed spray administration requires large doses of oocysts. Uniform exposure of the flocks to the vaccine cannot always be achieved.
Vaccine may also be administered through the use of water proportioning systems including automatic fountains and automatic water medicator or proportioners. However, given the particulate nature of coccidiosis vaccines, it is doubtful that the vaccine may actually make it to the distal end of the water line, resulting in uneven exposure to the flock. Additionally, administration of the vaccine through the water proportioning system requires that after administration of the vaccine, the proportioning system be thoroughly cleaned to remove any residual vaccine.
The administration of vaccine in the drinking water requires that the oocysts remain suspended to provide for even exposure to the flock. One solution to this has been proposed by the present applicant in Canadian Patent 1,204,057, which involves suspending the oocysts in a 1.5% carrageenan solution. While this method has numerous advantages, such as reduced levels of oocysts necessary to provide immunization, as well as ease of administration, there is still a drawback in that the provision of open watering systems to hatchlings could result in the liquid being spilled or wetting the hatchlings, which could potentially affect the health of the hatchlings, especially in cold weather and during transportation when hatchlings are vaccinated in the hatchery.
Another method of administering vaccine is through the use of a spray cabinet, which is utilized in the hatchery to spray the hatchlings with a liquid form of the vaccine. A flat or tray of hatchlings usually containing about 100 birds is placed in the spray cabinet and a predetermined dose of liquid vaccine is sprayed directly on the birds. It is expected that as the birds preen they will ingest the vaccine from their feathers. This method suffers some drawbacks in that uniform exposure of all of the hatchlings may not be easily achieved because constant stirring is required to keep oocysts suspended just before spraying. In addition, as the birds are being sprayed with a water-suspended vaccine, then there is a risk that the hatchlings may become too wet, which may affect the health of the birds.
A gel form of a coccidiosis vaccine has been described in PCT application WO 96/25,951, published Aug. 29, 1996. The gel form vaccine of this application is a self-supporting or sliceable vaccine which is formed into a cylinder which is, in turn, sliced to give a proper amount of the vaccine for each tray of the hatchlings. Alternatively the vaccine may be gelled into a suitable watering trough. While this vaccine overcomes the potential problem of wetting of the birds, it does require that the hatchery workers handle the gel to place it in the hatchery tray.
Thus, there remains a need for a simplified means for administration of therapeutic agents in soft gel form to hatchlings in the hatchery, which provides adequate exposure of the flock to the therapeutic agent while reducing potential problem areas.